Lithium ion batteries used in various industrial fields including various electronic devices use a lithium metal salt containing manganese, nickel and cobalt as a positive electrode active material. The lithium ion batteries are formed by enclosing circumferences of a positive electrode material containing the positive electrode active material and a negative electrode material in a housing containing aluminum. Recently, with an increased amount of lithium ion batteries to be used and expansion of the range of use, an amount of the lithium ion batteries to be discarded has been increased due to product life of the batteries and defects in the manufacturing processes.
Under such circumstances, there is a need for easily recovering expensive elements such as nickel and cobalt as stated above from a large amount of discarded lithium ion battery scrap with a relatively low cost in order to reuse the elements.
In order to treat the lithium ion batteries such as the lithium ion battery scrap for recovering the valuable metals, a preliminary step is firstly carried out by roasting the lithium ion batteries to remove a harmful electrolytic solution contained therein so as to render the lithium ion batteries harmless, and then sequentially crushing and sieving the lithium ion batteries to remove a certain degree of aluminum contained in the housing and the positive electrode base material.
A leaching step is then carried out by leaching the powdered positive electrode material obtained in the previous step with an acid, and dissolving lithium, nickel, cobalt, manganese, aluminum and the like that may be contained therein in the solution to obtain a leached solution.
Subsequently, a recovery step is carried out to separate each metal element being dissolved in the leached solution. In this case, the leached solution is sequentially subjected to a plurality of stages of solvent extraction or neutralization depending on the metals to be separated and each solution obtained in each stage is subjected to stripping, electrolysis, carbonization or other treatments, in order to separate each metal being dissolved in the leached solution. More particularly, each valuable metal can be recovered by firstly recovering aluminum, then manganese, then cobalt, and then nickel, and finally leaving lithium in the aqueous phase.